Dissolved organic matter (DOM) such as fulvic acid (FA)
and humic
acid (HA) in soil considerably affects the fate of per- and polyfluoroalkyl
substances (PFASs). However, the effect of DOM on their behavior in
plants remains unclear. Herein, hydroponic experiments indicate that
FA and HA reduce the accumulation of an emerging PFAS of high concern,
6:2 chlorinated polyfluoroalkyl ether sulfonate (6:2 Cl-PFESA), in
wheat roots by reducing its bioavailability in the solution. Nevertheless,
FA with low molecular weight (MW) promotes its absorption and translocation
from the roots to the shoots by stimulating the activity and the related
genes of the plasma membrane H+-ATPase, whereas high-MW
HA shows the opposite effect. Moreover, in vivo and in vitro experiments indicate that 6:2 Cl-PFESA undergoes
reductive dechlorination, which is regulated mainly using nitrate
reductase and glutathione transferase. HA and FA, particularly the
latter, promote the dechlorination of 6:2 Cl-PFESA in wheat by enhancing
electron transfer efficiency and superoxide production. Transcriptomic
analysis indicates that FA also stimulates catalytic activity, cation
binding, and oxidoreductase activity, facilitating 6:2 Cl-PFESA transformation
in wheat.